100分！各位大哥帮忙啊！老师让我们做一个“计算器”？怎么做了？谢谢！
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现在J2SE的都忘啦
import java.awt.event.*;
import java.awt.*;
public class Calculate extends JFrame
implements ActionListener{
private JTextField display=new JTextField();
private JButton[] buttons=new JButton[16];
private String[] keys={"7","8","9","/",
"4","5","6","*",
"1","2","3","-",
"0","C","=","+"};
//to store the 2 inputs;
private String numStr1="";
private String numStr2="";
//to store the result or mid-result;
private String rstStr="";
//to define the first input is finished;
private boolean symb=false;
//to store the op;
private char op;
public Calculate(){
//Create the Frame;
setTitle("My Calculate");
setSize(230,200);
//Get the pane;
Container pane=this.getContentPane();
pane.setLayout(null);
//add the display;
display.setSize(200,30);
display.setLocation(10,10);
pane.add(display); //add the buttons;
int x=10,y=40;
for(int i=0;i<16;i++){
buttons[i]=new JButton(keys[i]);
buttons[i].setSize(50,30);
buttons[i].setLocation(x,y);
buttons[i].addActionListener(this);
pane.add(buttons[i]);
if(i%4!=3){
x+=50;
}
else{
x=10;
y+=30;
}
}
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE); }
//implements the interface
public void actionPerformed(ActionEvent e){
String str=String.valueOf(e.getActionCommand());
char ch=str.charAt(0);
switch(ch){
case '1':case '2':case '3':
case '4':case '5':case '6':
case '7':case '8':case '9':case '0':
if(!symb){
numStr1+=ch;
display.setText(numStr1);
}
else{
numStr2+=ch;
display.setText(numStr2);
}
break;
case '/':case '*':case '-':case '+':
op=ch;
symb=true;
break;
case 'C':
display.setText("");
numStr1=numStr2="";
symb=false;
break;
case '=':
rstStr=evaluate();
display.setText(rstStr);
try{
int temp=Integer.parseInt(rstStr);
}
catch(NumberFormatException e2){
numStr1="";
numStr2="";
symb=false;
break;
}
numStr1=rstStr;
numStr2="";
break;
}
} //used to evaluate the result;
private String evaluate(){
int result=0;
try{
int num1=Integer.parseInt(numStr1);
int num2=Integer.parseInt(numStr2);
switch (op){
case '+':result=num1+num2;
break;
case '-':result=num1-num2;
break;
case '*':result=num1*num2;
break;
case '/':result=num1/num2;
break;
}
return String.valueOf(result);
}
catch(ArithmeticException e){
return "ERROR:"+e.getMessage();
}
catch(NumberFormatException e){
if(numStr1.equals(""))
return "ERROR:Invalid First Number";
else
return "ERROR:Invalid Second Number";
}
catch(Exception e){
return "ERROR";
}
}
public static void main(String args[]){
Calculate myCalculate=new Calculate();
}
}
基础的计算器是需要处理的，一般有几个方法：
1。采用逆波兰表达式，然后用两个堆栈做运算
2。采用迭代函数，道理和上面一样，只是堆栈不在堆里面完成，而是通过迭代实现
3。采用binary tree做，这个比较有效率，而且科学。我建议用这个。叶子是变量，每个节点是运算符，binary tree根据operator的优先度构造这个应该是大学的作业，我大一的时候做过了，不过代码是C
java计算器
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class calculation extends JFrame
{public calculation() /*构造方法*/
{super("计数器");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initTextPanel(); /*文本框*/
initControlPanel(); /*控制键*/
initKeyPanel(); /*数字和运算符*/
Container pane = getContentPane();
pane.setLayout(new BorderLayout());
pane.add(TextPanel,BorderLayout.NORTH);
pane.add(ControlPanel,BorderLayout.CENTER);
pane.add(KeyPanel,BorderLayout.SOUTH);
pack();
try
{UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
}
catch(Exception ex)
{;} /*设置Windons观感*/
SwingUtilities.updateComponentTreeUI(this);
setResizable(false);
setVisible(true);
}
private void initTextPanel() /*设置文本框*/
{ TextPanel=new JPanel();
TextPanel.setLayout(new FlowLayout());
Resultarea =new JTextField("0",25);
Resultarea.setEditable(false); /*设置不可编辑*/
Color color=Color.white;
Resultarea.setBackground(color); /*颜色*/
Resultarea.setHorizontalAlignment(JTextField.RIGHT); /*设置显示位置*/
TextPanel.add(Resultarea);
}
private void initControlPanel() /*设置控制键*/
{ControlPanel=new JPanel();
ControlPanel.setLayout(new GridLayout(1,3,4,4));
JButton b1=new JButton("Backspace"); /*Backspace键*/
b1.setFont(font1);
b1.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent e)
{String s1=Resultarea.getText();
int l=s1.length();
Resultarea.setText(s1.substring(0 ,l-1));
}
});
ControlPanel.add(b1);
JButton b2=new JButton("CE"); /*CE键*/
b2.setFont(font1);
b2.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent e)
{Resultarea.setText("0");
isNew=true;
}
});
ControlPanel.add(b2);
JButton b3=new JButton("C"); /*C键*/
b3.setFont(font1);
b3.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent e)
{Resultarea.setText("0");
pnum="";
operation="";
isNew=true;
}
});
ControlPanel.add(b3);
}
{String key[] = {"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};
KeyPanel = new JPanel();
KeyPanel.setLayout(new GridLayout(4,5,4,4));
for(int i=0;i<20;i++)
{String label = key[i];
JButton b = new JButton(label);
b.setActionCommand(key[i]);
b.setFont(font2);
KeyPanel.add(b);
b.addActionListener(new ActionListener() /*无名监听器*/
{public void actionPerformed(ActionEvent e)
{Key_actionPerformed(e);
}
});
}
}
public void Key_actionPerformed(ActionEvent e) /*数字键和运算符键无名监听器*/
{String s=(e.getActionCommand());
String st=Resultarea.getText();
if(s.equals("0")) /*输入数为0*/
{if(st.equals("0"))
return;
else
{if(!isNew)
Resultarea.setText(st+"0");
else
Resultarea.setText("0");
}
isNew=false;
return;
}
if(s.equals("+/-")) /*输入数为+/-*/
{double k=Double.parseDouble(st);
{if(k!=0)
display(-k);
}
return;
}
if(s.equals("1")||s.equals("2")||s.equals("3")||s.equals("4")||s.equals("5")||s.equals("6")||s.equals("7")||s.equals("8")||s.equals("9")) /*输入1-9*/
{if(!isNew)
Resultarea.setText(st+s);
else
{ Resultarea.setText(s);
isNew=false;
}
return;
}
if(s.equals(".")) /*输入小数点*/
{if(Resultarea.getText().indexOf(".")==-1) /*不存在小数点*/
{if(isNew)
{Resultarea.setText("0.");
isNew=false;
}
else
Resultarea.setText(st+".");
}
return;
}
isNew=true; /*按下运算符，输入新的数*/
if(s.equals("="))
{compute(s);
operation="";
}
else
{if(s.equals("+")||s.equals("-")||s.equals("*")||s.equals("/")) /*二目运算符号*/
{if(operation.equals(""))
{pnum=Resultarea.getText();
operation=s;
}
else
compute(s);
}
else /*一目运算*/
{Count count1=new Count(Double.parseDouble(st));
if(s.equals("sqrt"))
{
display(count1.sqrt());
}
else
{if(s.equals("1/x"))
{if(st.equals("0"))
{Resultarea.setText("除数不能为0.");
operation="";
pnum="";
}
else
display(count1.reciprocal()); /*求倒数*/
}
else
display(Double.parseDouble(st)/100); /*输入%，使当前显示的值除于100*/
}
}
}
}
private void compute(String s)
{if(s.equals("="))
{if(operation.equals(""))
return;
}
double data1=Double.parseDouble(pnum);
double data2=Double.parseDouble(Resultarea.getText());
Count count2=new Count(data1,data2); /*加减乘除计算*/
if(operation.equals("+"))
display((count2.plus()));
else
{if(operation.equals("-"))
display((count2.minus()));
else
{if(operation.equals("*"))
display((count2.multiply()));
else
if(operation.equals("/"))
{if(data2==0)
{Resultarea.setText("除数不能为0");
operation="";
pnum="";
return;
}
else
display((count2.divide()));
}
}
}
operation=""; /*符号为当前符*/
pnum=Resultarea.getText();/*运算数为当前文本数*/
}
public void display(double result) /*显示输出方法*/
{int a=(int)result;
if(a==result)
Resultarea.setText(String.valueOf(a));
else
Resultarea.setText(String.valueOf(result));
if(Resultarea.getText().equals("NaN"))
Resultarea.setText("输入函数无效");
}
private JPanel TextPanel; /*文本框棉板*/
private JTextField Resultarea; /*文本框*/
private JPanel ControlPanel; /*控制键键面板*/
private JPanel KeyPanel; /*数字键和运算符键面板*/
private Font font1=new Font("Dialog",0, 10); /*控制键字体*/
private Font font2 = new Font("Dialog",0,10); /*数字键和符号键字体*/
private String pnum=""; /*前操作数*/
private boolean isNew=true; /*控制是否是新数*/
private String operation=""; /*运算符*/
}
class tester /*测试类*/
{
public static void main(String[] args)
{
new calculation();
}
}